Tissue Types
Key Terms
• Differentiation = produces specialized cells
during embryonic development
• Tissues = groups of cells which are similar in
structure and which perform common or
related functions
• Histology = the study of tissues
Four Basic Kinds of Tissues
•
•
•
•
Epithelial Tissue
Connective Tissue
Muscle Tissue
Nervous Tissue
Epithelial Tissue
• Locations:
– Covers the body
– Lines organs, body cavities, and ducts
– Forms glands
• Functions:
– Protection from injury and microbial invasion
– Regulates permeability
– Secretes fluids to lubricate structures
Epithelial Tissue
Characteristics:
• Avascular (no blood vessels)
• Cells may show polarity (apical & basal surface,
they are chemically and structurally different
from one another)
• A basement membrane attaches epithelia to
underlying connective tissues
• High rate of cell division (allows repair by
sloughing off dead or injured cells, important
because epithelium is exposed to physical stress)
The Polarity of Epithelial Cells
Classification of Epithelia
• Number of cell layers pg 113
– Simple (single layer)
– Stratified (several layers)
– Pseudostratified (nuclei are at different levels & not
all cells reach the apical surface)
• Shape of cells (draw, location, function)
– Squamous (thin, flat, irregular cells) pg 115
– Cuboidal (cube shaped cells) pg 116
– Columnar, ciliated and nonciliated (tall & slender
cells) pg 116, 117
– Transitional (change shape from flat to cuboidal and
back) pg 119
Squamous Epithelia
Cuboidal Epithelia
Cuboidal Epithelia Cont.
Special Cuboidal Epithelia:
Transitional Epithelia
cells can stretch
Columnar Epithelia
Columnar Epithelia
Columnar Epithelia
Glandular epithelia
Many epithelia contain gland cells that produce
secretions
Exocrine glands:
– Produce secretions such as mucus and/or watery
solution through ducts onto the epithelial surface
Endocrine glands:
– Ductless, release secretions directly into bloodstream
Exocrine vs.
Endocrine
Glands
Examples of Exocrine Glands
Time to Review
Simple squamous
epithelium (lining of body
cavities)
Simple cuboidal epithelium
(lining of glands and ducts)
Simple columnar
epithelium (lining of
stomach, intestines)
Stratified squamous epithelium (skin)
Simple
columnar
epithelium
(lining of
digestive tract)
Simple cuboidal
epithelium
(lining of ducts in
kidneys)
Simple squamous
epithelium (lining
of the heart)
Pseudostratified
columnar
epithelium
(lining of nasal
cavity)
Transitional
epithelium (urinary
bladder)
Stratified
squamous
epithelium (lining
of mouth)
Type of Tissue
Function
Location
Pseudostratified
columnar
removing dust and particles lines the respiratory
from airways, has cilia
passageways
Simple Columnar
Absorption
Simple Cuboidal
Secretion and Absorption
Simple Squamous
Diffusion and Filtration
Stratified Squamous
Protects underlying cells
lines the uterus and
most organs of the
digestive tract
glands, kidney tubules,
ovaries
lungs, walls of
capillaries and vessels
skin(keratinized) and
the throat, vagina,
mouth (soft)
Stratified Cuboidal
Protection
lines ducts of the
mammary glands,
sweat glands, pancreas
Stratified Columnar
Protection, secretion
male urethra and vas
deferens, parts of the
pharynx
Transitional
(unstretched)
Specialized to become
distended
urinary tract